The invention generally relates to medical infusion devices. In particular, it relates to injection or infusion sites for infusing liquids into a patient.
During the course of medical treatment, it is often necessary to infuse medicinal or nutritional fluids into a patient. It may be necessary to infuse such substances repeatedly or over extended time periods. This is usually done by inserting an indwelling catheter into the body, often the vasculature. Fluids may then be infused repeatedly without the need for repeated piercing of the skin, veins or arteries and the trauma associated with such procedures. Such an indwelling catheter is typically provided with an injection or infusion site which allows a needle or cannula to be inserted and withdrawn as needed so that fluids can be infused through the catheter. Such an injection or infusion site is known as a "PRN" or "pro re nata" (from the Latin for "as the occasion arises") site.
PRN sites are well known in the art. The most commonly used PRN comprises a rubber or silicone septum. Such a PRN is used by penetrating the septum with a hypodermic needle to infuse the fluid. On withdrawal of the needle, the septum reseals itself due to the elasticity of the septum and the fact that the hole made by piercing the septum is very small.
In recent years concern has grown about the risks of infection to health care workers presented by sticks by contaminated needles. Attempts have been made to provide protective shields for needles specifically used for intravenous infusion. U.S. Pat. No. 5,084,032 shows an example of such a system. Another approach is to provide an injection site which shields the nurse or doctor's fingers. An example of this approach is shown in U.S. Pat. No. 5,078,694.
A further approach to avoiding needle sticks resulting from the use of intravenous infusion sets is to use an infusion site having a pre-split septum in conjunction with a blunt cannula rather than one requiring the septum to be pierced by a sharp needle. Examples of this approach are found in International Patent Applications published under the Patent Cooperation Treaty under International Publication Nos. WO 89/06553 and WO 90/11103.